Means for regulating electrically-operated driving systems.



J. G. MAOFARLANE, H. BURGE 6; A. WILLIAMS. MEANS EOE REGULATING ELEGTRIGALLY OPERATED DRIVING SYSTEMS. APPLICATION FILED DEG. 22, 1911.

1,019,677, H Patented Mar.5, 1912.

UNITED STATES PATENT OFFICE.

JAMES COLQUHOUN MACFARLANE ,AND HARRY BURGE, OF CHELMSFORD, AND ALAN WILLIAMS, O]? LONDON WALL, LONDON, ENGLAND, ASSIGNOBS T0 CBOMPT'ON & COMPANY, LIMITED, 015 CHELMSFORD, ENGLAND.

MEANS FOR REGULATING ELECTBICALLY-OPERATED DRIVING SYSTEMS.

To all whom it may concern:

-Be it known that we, JAMES CoL UHoUN MACFARLANE and HARRY BURGE, residing at Arc Works, Chelmsford, in the county of Essex, England, and ALAN WILLIAMS, residing at Salisbury House, London Wall, London, England, all subjects of the King of Great Britain, have invented certain new and useful Improvements in Means for Reg.- ulating Electrically-Operated Driving Systems, of which the following is a specificat-ion.

This invention relates to electrically-operated driving systems wherein wide variations in torque and speed occur while the demand for power from the supply is restricted, and the invention has for its object to provide means for improving the regulation and torque-"of the working motors in such systems.

Electrically-operated hauling or winding machinery, or electrically-operated rolling mills, possess the characteristics above referred to, and the invention will be hereafter described, by way of example, in connection therewith.

The invention consists primarily in the provision of'an auxiliary field winding on the working motor so arranged that, at low speeds a powerful field is produced giving the torque necessary to produce acceleration, such field strength diminishing as the speed increases and becoming a minimum at the full speed of the motor.

The accompanying drawing illustrates diagrammatically the application of the invention to, say, a colliery winding plant.

G represents a generator of the direct cur rent type provided with a variable field excitation A and a hand cont-rolled resistance B so that it iscapable of delivering its current at any desired voltage, and E is an exciter directcoupled to the generator and developing exciting current at a constant voltage.

X and Y are supply conductors connected to the brushes of the generator G and leading current to the motor M, of which the conductor X may be regarded as at zero potential and the conductor Y may be regarded as having say, the potentia produced by the generator G the magnitude of which depends upon the amount of excitation and the speed of such generator.

Specification of Letters latent.

a potential V, that is to Patented Mar. 5, 1912.

Application filed December 22, 1911. Serial No. 667,368. I

of the exciter E or from any other suitable source of constant current supply and therefore traversed by a constant .currentthe potential across its terminals being V that is to say, the constant voltage ofthe exciter or other source of supply. A second windmg F is provided and is connected from the positive brush of the vexciter or from the positive pole of the supply to the conductor Y, the voltage at the terminals. of this winding is the difference between the voltages at' the positive brush of the exciter or the positive pole of the source of supplyand .the positive brush of the generator, that is to say, is-equal to VV Consequently the current in this winding vanishes when the generator potential is equal to the exciter or the supply potential and changes sign when the. generator potential exceeds the exciter or supply potential so as to actually produce a demagnetizing action. In combination with this winding of the motor fieldwe find it advantageous to employa demagnetizing series winding on the field of the generator G as shown at L which current. This demagnetizing series field Y winding L, under ordinary running conditions, operates to reduce the potential V of conductor Y and thereby to increase the potential V V at the terminals of the winding F But when regeneration occurs, that is to say, when the working mot-or M tends to return current'to the line, the demagnetizing series winding L operates to increase the potential V of conductor Y and consequently to reduce the potential V* g at the terminals of the winding F By this means limit current conditions are obtained.

From the foregoing, it will be understood that the working motor M has a relativelyhigh torque when running at low speed, as the voltage of the generator is then regulated to a very low value by the variable resistance B and, hence, the motor field will be excited by the motor field winding F and also by the motor field winding F? owing to the higher vvoltage of the exciter as compared to that of the generator which will cause the exciter current to flow through the winding F in a direction to magnetize the motor field, and this high torque of the mothe current will then flow through the motor I field Winding F 2 in an opposite direction, thereby reducing the exciting eflect of the motor field winding F this demagnetizing effect of the motor field increasing with the increase in voltage of the generator and thus producing automatic regulation of the motor. By using the series demagnetizing winding L for the generator field in combination with the motor field windings herein described, a limitation is placed on the demand of current from the generator by the motor and a regenerative braking effect is also obtained. For example, as the amount of current flowing from the generator to the motor increases, the field strengthand consequently the current output of the generator is reduced by the flow of such current through the generator field winding L which then has a demagnetizing effecton the generator field, and should the motor operate in a manner to produce a regenerating effect or a tendency to produce a counter-electromotive force, the field winding L of the generator operates to increase the potential of the generator current in the conductor Y and thus oppose the tendency of the motor to return current to the line.

What we claim is. e

1. Electrically-operated driving apparatus of the class described comprising, in combination, a direct current generator, means for exciting the field thereof, a motor, means for connecting the armature thereof to said generator, and a field winding for said motor having its terminals connected to the positive poles of the generator and excitin means respectively.

2. Electrically-operated driving apparatus of the class described comprising, in combination, a direct current generator having a field rovided with means for varying the excitation thereof whereby said generator may deliver current at difierent voltages, means for exciting the field of said generator, a motor connected to receive current from said generator and having a constant excitation winding and also a field winding, the latter having its terminals connected to the poles of like polarity of said generator and exciting means respectively;

3. Electrically-operated driving apparatus of the class described com rising, in combination, a direct current ge erator, exciting means connected to the field of the generator, a motor connected to receive current from the generator and having a field winding connected to the poles of like polarity of the generator and said excitmg -means, and a de-magnetizing field winding for the generator connected in series between the generator and motor.

In testimony whereof we have hereunto set our hands in presence of two-subscribing Witnesses.

JAMES commons murmurs. HARRY BURGE. ALAN WILLIAMS.

Witnesses:

NEVILLE E. Brooms, ERNEs'r Jenn HILL. 

